Development and cleaning apparatus for reverse path machine

ABSTRACT

A member with a developable image thereon is passed through a development and cleaning station two times; once in one direction and then in the opposite direction. Development of this image with toner particles and wiping and cleaning of the toner particles from the background areas into the image areas and from the member is performed during each pass through the development and cleaning station. A development member and cleaning members, located on each side of the development member in the direction of the path of travel of the image retaining member, perform the above function.

United States Patent 1 1 Eichorn, deceased et al.

1 1 DEVELOPMENT AND CLEANING APPARATUS FOR REVERSE PATH MACHINE [75]Inventors: Roger H. Eichorn, deceased, late of Webster, N.Y.; LincolnFirst Bank of Rochester, executor, Rochester, NY.

[731 Assignee: Xerox Corporation, Stamford,

Conn.

[22] Filed: Dec. 27, 1973 [21] Appl. No.: 428,975

[52] US. Cl 118/637; 427/14; 355/3 DD [51] Int. C1. G03G 13/00 [58]Field of Search 118/637; 117/125;

V [56] References Cited UNITED STATES PATENTS 3,592,675 7/1971 Tung-namCheng ll7/l7.5 3,672,763 6/1972 Levene et al. 118/637 1 Dec. 2, 19753,698,926 10/1972 Masayoshi Furuichi ll7/17.5 3,705,767 12/1972 Tamai eta1 118/637 T896011 3/1972 York et a1 355/15 Primary Examiner-MervinStein Assistant E.\'aminerSteven Hawkins Attorney, Agenl, 0r Firm-JamesJ. Ralabate; Clarence A. Green; Sheldon F. Raizcs [57] ABSTRACT A memberwith a developable image thereon is passed through a development andcleaning station two times; once in one direction and then in theopposite direc tion. Development of this image with toner particles andwiping and cleaning of the toner particles from the background areasinto the image areas and from the member is performed during each passthrough the development and cleaning station. A development member andcleaning members, located on each side of the development member in thedirection of the path of travel of the image retaining member, performthe above function.

6 Claims, 3 Drawing Figures U.S. Patent Dec. 2, 1975 Sheet 1 of33,923,004

US. Patent Dec. 2, 1975 Sheet 2 of 3 3,923,004

FIG. 2

Sheet 3 of 3 3,923,004

US Patent Dec. 2, 1975 DEVELOPMENT AND CLEANING APPARATUS FOR REVERSEPATH MACHINE DESCRIPTION OF THE INVENTION It is an object of thisinvention to provide a copying apparatus which has a reverse path imagecontaining member with a mechanism which develops the image and removesparticles from the background area into the image area on each pass ofthe image containing member through a development and cleaning station.This allows for a faster speed of the image containing member past thedevelopment and cleaning station with adequate exposure to development.

Other objects of this invention will become apparent from the followingdescription with reference to the drawings wherein:

FIG. 1 is a general schematic view of a copying apparatus embodying thepresent invention;

FIG. 2 is a partial view of the copying apparatus of FIG. 1 illustratingthe position of a web after an image thereon has been developed; and

FIG. 3 is a view of the copying apparatus of FIG. 1

. during transfer of a developed image to a copy medium.

Referring to FIG. 1, a web of heat sensitive material is fed from asupply spool 12 around idler rolls 14, 16,18, and 22 to a take-up spool24. The web 10 comprises a support with a heat sensitive coating. Forexample, the support may be an organic film such as a polyester film,cellulose acetate or triacetate film coated with a delayed tack adhesivewhich is normally hard and non-tacky at room temperature, but which,upon being activated by heat to a tacky condition and subsequentlycooled to room temperature, thereafter remains tacky for considerableperiods of time varying from at least seconds to several days or moredepending upon the particular composition involved. Such delayed tackcoatings are well known and can be a mixture of discrete particles ofresin, such as indene resin or esterified resin, and discrete particlesof crystalline plasticizer, such as diphenyl phthalate or N- cyclohexylparatoulene sulfonamide. The particles are bound together into thesupporting film by a binder, such as styrene-butadiene copolymer.Generally speaking, the crystalline plasticizer component of the mixtureis in excess of the resin component.

The supply spool 12 and the take-up spool 24 are connected through arespective slip clutch (not shown) to a reversible motor (not shown).The clutch connection for the supply spool 12 is such that the spoolwill be positively driven in a counter clockwise direction and slips toallow the spool to rotate in a clockwise direction. The clutchconnection for the take-up spool 24 is such that the spool will bepositively driven in a clockwise direction and slips to allow the spoolto rotate in a counter clockwise direction.

A rotatable cylinder 26 having a highly reflective surface, which may bereversibly driven, is interposed between the idler rolls l6 and 18 andis so arranged that the web 10 is pressed against the idler rolls toform nips 17 and 19. An incandescent lamp 28 is located opposite thecylinder 26 and a reflector 30 is arranged to focus the rays of the lamp28 onto the cylinder 26 between the idler rolls 16 and 18.

A developing station is provided which comprises a developer housing 32having a bed of ferromagnetic toner particles 34 therein. The tonerparticles 34 comprise thermoplastic particles pigmented with carbonblack or other radiation absorbing dyes or pigments, and mixed with ironoxide particles.

Two synthetic or fur fibrous cleaning brushes 36 and 38 and a well knownmagnetic brush 40 are rotatably mounted to the side walls of the housing32. The upper wall 42 of the housing has three openings 44, 46 and 48through which a portion of the cleaning brush 36, the magnetic brush 40,and cleaning brush 38 extend, respectively. All of these brushes arearranged to wipe against the web 10 as it passes thereby.

A stationary keeper plate 50 is provided opposite the developer housing32 and keeps the web 10 in position to be engaged by the cleaningbrushes 36 and 38 and the magnetic brush 40.

A stack of copy sheets 52 is located on a paper tray 54. The stack ofsheets are urged by a torsion spring 56 against a paper feed roll 58.The paper feed roll 58 drives the uppermost sheet of the stack along aguide 60 to a pair of nip rolls 62 which receive the leading edge of thecopy sheet therein. At the proper time, the nip rolls 62 are actuated todrive the copy sheet to the nip 19. A storage recess 64 is provided inthe guide 60 to allow the sheet to buckle until the nip rolls 62 areactuated.

An original inlet slot 66 is provided which opens adjacent the nip l7and an original outlet slot 68 is provided which opens adjacent the nip19. A copy outlet opening 70 is provided which is also adjacent the nip17. A microswitch 72 is provided in the original inlet opening 66 which,when actuated, serves to actuate a control mechanism (not shown) whichperforms the following operation:

Referring to FIG. 1, an original sheet 74 having an image thereon is fedinto the inlet slot 66 actuating the switch 72 which sets in motionrotation of the cylinder 26 and the web supply roll 12 and the webtake-up roll 24, the cleaning brushes 36 and 38 and the magnetic brush40 in the direction of the arrows. Also, actuation of this switch 72activates the lamp 28. The leading edge of the original sheet 74 is fedinto the nip 17 and is moved with the web 10 past the lamp 28 and thenthe original separates from the web and is directed through the outletopening 68. As the web and original pass the lamp 28, heat is absorbedby the image and transferred to the heat sensitive web 10 to form atacky image corresponding to the image on the original sheet. As the web10 and the original 74 pass around the cylinder 26, the sandwich is intight engagement with the cylinder 26 assuring efficient heat transferbetween the image and the heat sensitive layer. The web is transportedpast cleaning brush 38 which has no effect thereon and then past themagnetic brush 40 which presents toner particles to the web and developsthe tacky image thereon. Thereafter, the web is moved past the cleaningbrush 36 which wipes toner particles from the background areas into theimage areas, thereby cleaning the background areas and adding tonerparticles to the image areas. During development, the portion of the webpassing the cleaning and magnetic brushes takes support on the keeperplate 50 which assures that the toner particles presented by themagnetic brush will engage the web and that the cleaning brushes engagethe web. The control system employs a camming mechanism (not shown)which assures that the lamp 28 is illuminated for a sufficient time forthe imaging process to be completed and then the lamp is turned off.Referring to FIG. 2, the camming mechanism also assures that asufficient length of the web corresponding to the length of the sheet tobe copied passes at least the cleaning brush 36 prior to stopping with aportion of the leading edge of the developed image being wrapped on thetake-up roll 24 as a single layer only to avoid any smudging of thedeveloped image. To illustrate this, the leading edge of the developedimage is indicated by reference numeral 76 and the trailing edge isindicated by reference numeral 78.

After the web 10 has stopped, the rotation of the supply roll 12,take-up roll 24, cleaning brushes 36, 38, magnetic brush 40 and therotation of the cylinder 26 is reversed and the paper feed roll 58 isactuated to move the leading edge of the uppermost sheet of the stack 52into engagement with the nip rolls 62. The web 10 starts its reversemovement with the former trailing edge 78 now being the leading edge.The cleaning brush 36 engages the web 10 and has very little effectthereon, and then the magnetic brush 40 presents toner particles to theimage to develop the same where needed. Thereafter cleaning brush 38engages the web to perform the same function as performed by the brush36 when the web 10 passed through the station in the opposite direction.As the leading edge 78 of the image moves toward the nip 19, the niprolls 62 are actuated at the proper time to move the copy sheet 52 tothe nip 19 so that the leading edge of the copy sheet 52 will align withthe leading edge 78 of the image just prior thereto. The lamp 28 isilluminated just prior to the leading edge 78 of the developed image andthe copy sheet entering the nip 19. The aligned copy sheet and the heatsensitive web are forwarded past the lamp 28 which radiantly heats thetoner particles whereby a substantial portion thereof are transfixed(transfer and become fixed) to the copy sheet to provide a reproductionof the original image. This transfixing occurs due to the pressurebetween the web 10 and the copy sheet 52 which is maintained as theytravel around the cylinder 26 and through the nip 17 combined with acorresponding proper temperature. As the copy sheet 52 emerges from thenip 17, the sheet separates from the web 10 and is directed out of themachine through the slot '70. After the trailing edge of the copy sheet52 has emerged from the nip 17, the lamp 28 is turned off, the nip rolls62, the cleaning and magnetic brushes stopped, and the rotation of theweb supply roll 12 and the take-up roll 24 is reversed to move the usedportion of the web 10 to a point where the edge 78 of the last imageformed on the web passes just beyond the nip 17 where the web is stoppedin position for another copy to be made in the same manner as describedabove.

Since toner particles are presented to the image on each pass followedby a cleaning brush, the speed of the web may be altered in eachdirection since the development does not occur in only one pass. Also,the image or development speed need not be dependent upon one another.

The control system and the components thereof for operating the machinein the manner described are all well known and well within the grasp ofone having ordinary skill in the art and, therefore, have not beenshown.

Since the imaging and developing function of the components of themachine is separate from the image transfer function, the intensity ofthe lamp 28 and the speed at which the web 10 travels in reverse can bechanged from the intensity and speed for the imaging and developingfunction depending upon for what results the machine is designed.Furthermore, the direc- 5 tion of rotation of the cleaning and magneticbrushes may be as desired for each pass of the web thereacross.

While this machine has been described utilizing an automatic paperfeeder, the machine also has utility where the copy sheet 52 is fed byhand into the machine. ln this instance, a pair of nip rolls may belocated in the slot 68 which rotate in one direction to withdraw theoriginal from the machine and rotate in the opposite direction at theproper time to pull a copy sheet inserted into the slot 68 to meet theleading edge 78 of the web just prior to the nip 19 for the transfer andfixing of the toner powder image from the web to the copy sheet.

It should further be realized that the concept of this invention is alsoapplicable to developing image bearing members in sheet form rather thanin web form as long as means are provided to reverse the path of travelof the sheet to pass through the development and cleaning station inopposite directions.

Rather than transfer the developed image to the copy paper, thedeveloped image may be fused onto the heat sensitive web 10. This may bedesired when a series of copies are needed in a specified sequence. Inthis respect, the surface of the cylinder 26 which will be contacted bythe toner particles during the fixing or fusing step must comprise amaterial to which melted toner particles will not stick. Alternatively,a stack of release sheets could be placed on the paper tray 54 and fedpast the lamp 28 in contact with the developed image. In this case, therelease sheet will be of a material to which the toner particles willnot stick.

What is claimed is:

l. A copier comprising the combination of a member having an imagingsurface for carrying latent images; reversible means for moving saidmember first in one direction and then in the opposite direction along apredetermined path;

development means positioned adjacent said path for applying imagedeveloping toner particles to said imaging surface as said member ismoving in said one direction and in said opposite direction;

first cleaning means positioned adjacent said path on one side of saiddevelopment means for removing toner particles from background areas ofsaid imaging surface as said member is moving in said one direction; and

second cleaning means positioned adjacent said path on the other side ofsaid development means for removing toner particles from backgroundareas of said imaging surface as said member is moving in said oppositedirection.

2. The copier of claim 1 wherein said first and second cleaning meanscomprise separate fibrous brushes which are maintained in contact withsaid imagining surface during movement of said member in said onedirection and said opposite direction.

3. The copier of claim 2 wherein said development means is a magneticbrush system having a rotatably driven roller for applying toner ladenferromagnetic developer to said imaging surface.

4. The copier of claim 1 wherein said development means is a magneticbrush system having a rotatably 6. The copier of claim 4 wherein saidimaging surface comprises a heat sensitive material for carrying tackylatent images.

1. A copier comprising the combination of a member having an imagingsurface for carrying latent images; reversible means for moving saidmember first in one direction and then in the opposite direction along apredetermined path; development means positioned adjacent said path forapplying image developing toner particles to said imaging surface assaid member is moving in said one direction and in said oppositedirection; first cleaning means positioned adjacent said path on oneside of said development means for removing toner particles frombackground areas of said imaging surface as said member is moving insaid one direction; and second cleaning means positioned adjacent saidpath on the other side of said development means for removing tonerparticles from background areas of said imaging surface as said memberis moving in said opposite direction.
 2. The copier of claim 1 whereinsaid first and second cleaning means comprise separate fibrous brusheswhich are maintained in contact with said imagining surface duringmovement of said member in said one direction and said oppositedirection.
 3. The copier of claim 2 wherein said development means is amagnetic brush system having a rotatably driven roller for applyingtoner laden ferromagnetic developer to said imaging surface.
 4. Thecopier of claim 1 wherein said development means is a magnetic brushsystem having a rotatably driven roller for applying toner ladenferromagnetic developer to said imaging surface.
 5. The copier of claim4 wherein said first and second cleaning means include separate fibrousbrushes engaged with said imaging surface.
 6. The copier of claim 4wherein said imaging surface comprises a heat sensitive material forcarrying tacky latent images.